1. Field of the Invention
The present invention relates to an open type fuel cell system with an unreacted material removing function, including a recirculating means recirculating unreacted material discharged from a main fuel cell into the main fuel cell, a regenerating means for removing moisture produced during the operation of the main fuel cell and impurities contained among re-circulated materials, and an exhausting means for exhausting a reductant, which is a fuel among the unreacted material remnants inside the regenerating means.
2. Description of the Related Art
A fuel cell refers to a system generating electricity through the reaction of an oxidizer and a reductant, which is a fuel (for example, a liquefied natural gas LNG, liquefied petroleum gas LPG, hydrogen, methanol, etc.), and simultaneously producing water and heat as a by-product, resulting in an electricity-generating device having high electric-generating efficiency and where environmentally harmful substances are removed.
And, according to the type of the electrolyte used, there exist a PEMFC (Polymer Electrolyte Membrane Fuel Cell), a DMFC (Direct Methanol Fuel Cell), a PAFC (Phosphoric Acid Fuel Cell), a MCFC (Molt Carbonate Fuel Cell) and a SOFC (Solid Oxide Fuel Cell).
Of such types of fuel cells, PEMFC, PAFC and DMFC are low in operating temperature, which is about 80° C. to 120° C., 190° C. to 200° C., and 25° C. to 90° C., respectively. These have high availability as an electric source of various modes of transportation (for example, automobiles), residential and commercial use and as a portable power source.
Therefore, in order to promote and expand the commercialization of these fuel cells, research attention is focused on the miniaturization and reducing of weight and cost of an entire fuel cell system.
However, since the production of reactants is excessive and supplying gas into a catalyst layer and diffusing proton into a polymer membrane are prohibited due to a plethora of moisture produced within the operating environment of a high-current area inside a fuel cell, a lowering of the performance of fuel cells is observed.
Significantly, a partial cell performance drop on account of uneven water distribution per unit cell existing in a fuel cell makes it difficult to perform a normal operation.
As such, considering that the excessive moisture produced in a fuel cell, flooding is an important factor causing the lowering of reaction efficiency. Because flooding makes the secure operation of fuel cells difficult, it is greatly needed to discharge the excessive moisture out of a fuel cell.
Hence, Korean Intellectual Property Office Registration No. 10-0509818-0000 discloses “a method and an apparatus for performing an internal purge in a fuel cell system.”
Briefly referring to the prior-art technology, such a system is configured to detect the voltage of a plurality of cells; purge a moisture and gas mixture, which exist inside a stack, out of the stack using a pressure difference that is achieved by controlling a purge valve and a recirculation pump upon a flooding occurrence; and re-supply moisture and separated gas into the stack.
However, such a prior-art technology encompasses following problems.
Firstly, a fuel purity supplied into a fuel cell fails to reach 100%; and thus, even if moisture and the separated gas are re-supplied into the fuel cell, in the end, impurities are stocked up inside the fuel cell, lowering generation efficiency.
Also, impurities such as metal ions, and particles of a peripheral apparatus composed of carbon and a fuel cell, constructing a bipolar plate and an electrode, stock up inside a fuel cell, gradually influencing the durability of the fuel cell as well as producing a current leakage inside a cell. This causes shortening or breakage of the fuel cell and produces an enormous repair cost, which seems to be undesirable.
Also, if recirculating gas inside a fuel cell and removing inside moisture produced in the fuel cell using a conventional technology, a closed circuit is constructed. In the end, impurities are flowed into the fuel cell again through the gas supplied into the fuel cell, lowering the performance and durability of fuel cells.
On the other hand, in the case of a general open-type fuel cell system unequipped with an interior purge, there is a need for a cautious long-time operation in a poorly ventilated or sealed space due to the explosion hazard of fuel such as unreacted hydrogen, discharged into the open air from the fuel cell.